The innate immune system is an evolutionarily ancient and highly conserved first line of host defense against pathogens in plants, fungi, insects and mammals. Innate immunity is essential for early responses to infection and effective immune responses, but is also an important contributor to acute and chronic inflammatory diseases. Furthermore, Innate Immune cells are also essential for development and regeneration. Over the past 10 years, our understanding of innate immunity has increased exponentially and it is now clear that abnormalities in this system underlie many disease processes. Furthermore, the emergence of antibiotic-resistant strains of bacteria, the need to develop novel vaccination strategies for new pandemics and the threat of bioterrorism have emphasized the need to understand the mechanisms by which hosts fight infection. For these reasons, a focused research program in innate immunity is timely, and we believe that Pediatrics at Massachusetts General Hospital (MGH) is ideally placed to deliver this. MGH has many researchers working in Innate Immunity, and a major concentration of researchers is present in the Developmental Immunology Program, in the Department of Pediatrics. Over the past decade, Developmental Immunology has had a strong track record of major advances in the field of Innate Immunity and has trained a number of investigators and developed junior faculty to independence, where they continue to make major contributions to this area. To continue to support the existing momentum in this field, we have initiated a five year strategic plan in Innate Immunity, aiming to create new research groups and develop research infrastructure. Although a faculty search was started in 2008, and resources and long-term support (years 3-5) are committed, recent financial constraints have restricted short-term funding, leaving us unable to move forward with this at the present time and complete our research program. In this grant we are seeking support for the recruitment and development of a new faculty member to build our core program in Innate Immunity research.